Governments should protect the essential goods from threats from foreign competition and instability because with out those goods the government will start to lose income. Without income from the taxes from these goods more jobs will dry up because less people are buy into the economy and paying taxes. It is a vicious cycle.
No, governments should not protect essential goods from foreign competition or instability, because governments are inherently bad at manipulating the economy. A government cannot say with certainty that a good is essential. If a good can be purchased cheaply elsewhere, people can save money and spend the money they save on other things. In the end, market forces balance it out. Manipulting the market is inefficient in the long run.